Get to Know the Big Dipper

Nov 19, 2018

International Space Station

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The Big Dipper is an old friend to most of us. Poetically, it is spring itself, the season of renewal, right now, when the Dipper is best seen. Go out between 9 and 10 p.m., and you’ll see that it hovers so high in the north, it’s almost overhead.

Where is the Big Dipper?

The Dipper floats forlornly in a dark desolate region of the sky. It’s actually a section of the Great Bear high in the North. This realm lies far from the Milky Way. Hence, the Dipper guides our eyes away from the flat plane of our own galaxy and toward the rest of the universe.

Because no foreground dust obscures the view, the Dipper’s direction offers a crystal-clear window to distant galaxies. That’s why the Hubble telescope’s famous 1995 deep-field photo stared at this place for 100 unblinking hours to capture objects at the edge of the observable universe. Their ancient light, fading like an old sepia print by cosmic expansion, brings us the latest news from an era that no longer exists.

The second star of the Dipper’s handle is the sky’s most famous double star: Mizar and Alcor. The ability to discern this “horse and rider” was an old Arabic test of keen eyesight. Either Alcor has brightened over the centuries or else the Arabs had vision problems, because away from city lights the pair is easy to see.

Most of the Dipper’s stars are not simply random line-of-sight alignments like most constellations, but family members forming a physical association—the very nearest star cluster to Earth.

Credit: VegaStarCarpentier/NASA

How Do You Find the North Star From The Big Dipper?

But its greatest fame is its ability to guide us to the most famous star in all the heavens. These nights, the two stars at the leftmost end of the Dipper’s bowl point downward to a solitary star of their same brightness: The North Star, Polaris. It shows you true north far more accurately than a compass.

About This Blog

Welcome to “This Week’s Amazing Sky,” the Almanac’s blog on stargazing and astronomy. Bob Berman, longtime and famous astronomer for The Old Farmer’s Almanac, will help bring alive the wonders of our universe. From the beautiful stars and planets to magical auroras and eclipses, he covers everything under the Sun (and Moon)! Bob, the world’s mostly widely read astronomer, also has a new weekly podcast, Astounding Universe!